The probability a student will pass Test 1 is 4/5.The probability that he will pass Test 2 is 3/4.The probability that he will pass both tests is 2/3.A.) What is the probability that he passes at least one test?

B.) What is the probability that he fails both tests?

A.) (4/5) + (3/4) = (31/20) - (12/20) = 19/20

B.) (1/5) x (1/4) = 1/20

Please correct me if I'm wrong, thanks!

Your calculations have assumed that the passing test 1 and passing test 2 are independent events. They are not: . So your answers are wrong.